2017 Volume 82 Issue 4 Pages 263-268
Five types of sulfate minerals, namely epsomite, metavoltine, sideronatrite, gypsum and jarosite were found on the core from the Ayukawa-Kita AK-1 well drilled in 1995. They were considered to be precipitated from the sulfuric acid formed by the oxidation of pyrite in the country rock. Their occurrence, powder X-ray diffraction pattern, chemical composition, solubility with water and hydrochloric acid are described in this paper. They should be easily identified as secondary products based on their occurrence, but some of them can be difficult to distinguish from some of the original rock-forming minerals by powder X-ray diffraction patterns, because of their similarities in the patterns. Therefore, it might be necessary to be familiar with secondary products of core samples for analysts. Furthermore, the first thing we have to do is to analyze and grasp the important information of core immediately after the sampling of core before they deteriorate.
